Hitting a Drywall

Florida's head toxicologist is trying to determine the physical effects of Chinese drywall on homeowners.

In the mid-1990s, while serving as an industrial hygienist and coordinator of the Florida Department of Health's Indoor Air Quality program, David Krause began hearing reports of soot-like deposits appearing on surfaces inside people's homes — in air-conditioning systems, refrigerators and freezers and even the walls. More puzzling, the black stains were often appearing in newly built homes.

Home builders, he recalls, were so befuddled by the recurring soot, or "ghosting," as it's also called, they were actually buying homes back from consumers.

David Krause [Photo: Ray Stanyard]

The culprit turned out to be mundane — household candles were producing the specks. Initially skeptical, Krause says, "We were able to demonstrate and actually reproduce it in brand new homes."

Krause has made a career of investigating "oddball contaminants" and unraveling riddles like the candle-soot mystery. For the past year and a half, he's been leading a probe of the possible health effects of Chinese-made drywall.

Complaints about sulfur-like odors and corroded copper wires and pipes in Florida homes began to trickle in to the Department of Health's division of environmental health during the summer of 2008. By December 2008, three months after Krause became state toxicologist, he faced a media firestorm as some homeowners claimed the Chinese drywall also was causing health problems, including coughing and irritation of the eyes, throat and sinuses.

It didn't take long for researchers to figure out how the drywall was corroding copper coils and blackening jewelry. As Krause explains, "Elemental sulfur in gypsum that was mined in China reacts with chemicals that are normally in the environment and releases these corrosive sulfur-containing gases that are uniquely attracted to copper."

It's been a trickier proposition, however, to separate real science from anecdotal evidence and determine what effects the chemicals in the drywall actually have on the body. "In the very beginning, we had very little hard data to evaluate it. What are the chemicals of concern? What are the exposures? What are the concentrations present in the homes?" he asks.

Working closely with the U.S. Environmental Protection Agency and the Centers for Disease Control — and
after reaching out to the private sector consultants who'd already begun looking into the problem themselves — Krause and his team devised a strategy to investigate the health effects of the drywall.

Conclusive answers, however, are still elusive. While the testing has uncovered hundreds of chemicals in every home, "so far, the data we have hasn't found any chemicals specifically that are above their known health thresholds or that would pose a specific hazard to the public or the specific people who live in those homes," Krause says.

He says his job is to make sure that the state acts on the basis of real scientific indicators. "My role in all this as state toxicologist is to bring a critical eye to the data and to provide guidance to the state surgeon general and administration as to where this lies in the spectrum of health hazards. Unfortunately, there's a lot of understandable emotion and concerns about this. The scariest thing for most people is the unknown. So it's been one of my biggest challenges to help uncover the unknown — to figure out what facts can we use to make a public health
decision."